Process for treating petroleum oil



Oct. 25, 1932. c. F. TEARS PRocEss Foa TREATING PETROLEUM oIL original Fiied June 18, 192s Patented Oct. 25, 1932 UNITED STATES P ATENT oFElcE CLAUDE I'. TEARS, OF CHICAGO, ILLINOIS, ASSIGNOB TO OIL PRODUCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION l' SOUTH DAKOTA PROCESS FOR TBEATING PETBOLEUH OIL application mea :fue 1s, 192s, semi no. $43,051. amena :february as, 192s.

This invention relates to improvements in a rocess for treating petroleum oils, and reers more particularly to the destructive distillation of hydrocarbon. oils to produce a product having the characteristics of gasoline and the like.

Among the objects of the invention are to rovide a process in which a char g stock 1s treated to cracking conditions o temperaloture and pressure, subsequently the fractionated vapors being partially condensed and introduced at a reduced pressure to a rerun tower, in whichv they are relieved of their lighter fractions, which are finally condensed to produce a uniform high quality distillate. The single figure is a diagrammatic side elevational view of the apparatus.

Referring to the drawing at 1 is shown a vheating coil' mounted in a furnace 2 which 2()l is connectedv by a transfer pipe 3 regulated by a valve 4 to an expansion chamber 5. The expansion chamber 1n turn is connected by a vpor line 6 controlled by a valve 7 to a deegmating column 8. The to of the ephlegmator is connected by a ine 9 in which is interposed a valve 10 to a partial condensing coil 11 mounted in the4 condenser box 12. The discharge end of this coil is connected by means of a transfer pipe 13 controlled by an expansion valve 14 to the rerun tower 15. The rerun tower in turn is connected by a vapor line 16 regulated by a valve 17 to a final condenser 18 positioned in a condenser box 19, this final condenser bein connected by a p'pe 20 controlled by a va ve 21 to the receiv' tank22.

In operation the chargmg stock is introduced through the line 23 controlled by a valve 24 from any convenient extraneous source, and is lcharged by means of the pump 25 through the line 26 to the heating coil 1 where it is raised to a conversion temperalture under substantial ressure.

' The oil on being ischarged from the heating coil passes through the transfer line 3 into the expansion chamber 5 in which it is collected in a substantial body, the vapors evolved therein, passin olf through the vapor line 6 to the dep legmator, while'the unvaporized products may be drawn of throu h either of the residuum lines 26 regulated y the valves 25.

The expansion chamber is equipped with try-cocks 27 for ascertaining the hquid level maintained therein. Upper and lower reymovable manhole plates on the chamber 5 furnish a means for cleaning the carbon accumulation resulting from the oil conversion. The vapors passing to the reiuxin column rise, and `in their travel are directe in a circuitous manner through the column due to the ositioning of alternate baiile plates 28 at intervals in the column. These plates serve to romote a partial condensation of the higher boiling point fractions,

which is further aided by the positioning of vto produce this cooling action.' The condensate separated out from the vapors during their travel through the fractionating or dephlegmating column collects in the bottom, and is drawn of through the lower leg of the dephlegmator 32 through the line 33 to be recycled with the charging stock to the heating stage. The overhead vapors passing from the top of the dephlegmator are directed through the line 9 to a partial condenser where their tem erature is somewhat reduced, and a parta condensation takes place. The purpose of this partial condenser 1s to cool the vapors prior to their introduction to the rerun tower'or fractionating column. The discharge end ofthe partial condenser has connection with the rerun tower '15 as explained, by transfer pipe 13 in which is interposed an expansion valve y'controlled 95 to relieve the pressure maintained upon the fluid discharge from the partial condenser to a pressure slightly above atmospheric. These fluid land va rous hydrocarbons are introduced centra y of the rerun tower which -is v:|00

preferably of a form diagrammatically disclosed in the drawing consisting of a well known type of bubble tower which is equipped with a plurality of decks 34 positioned at different levels in the tower, and having standpipes communicating between the separate levels to maintain separate pools of liquid levels on the respective decks. Cap risers such as those shown at 35 furnish a means for the vapors from the levels below to percolate through the pools of oil as they rise to the top of the column.

The rerun tower is preferably heavily insulated, and has a lower compartment 36 in which the liquid condensate collects, and in which is positioned a perforated steam coil -36a by means of which superheated steam is introduced to the tower to promote vaporization therein. In place of the steam coil, the lower portion of the tower may be enclosed in a furnace construction externally heated to produce vaporization of the condensate collecting in the lower portion 36. A substantial body of liquid oil may be maintained in the lowerportion 36 by suitably regulating the valves 43, 44 and 45 in the drawof lines 46 and 47, as well as by regulating the valves 48 and 49 in the liquid level control device 50. With the release of pressure on the oil as it is desired from the partial condenser, the Huid hydrocarbons will expand, certain fractions vaporizing and passing to the top of the column while other higher boiling point fractions will find their way to the lowest compartment 36 where they will be subjected to the increased temperature conditions maintained therein. The vapors rising to the top of the rerun tower pass over to the line 16 regulated by a valve 17 and are finally condensed in the'condensing coil 18, after which they are collected as liquid distillate in the receiver 22. The receiver is equipped with a pressure relief valve 37, a pressure gauge 38, a liquid level gauge 39 and a liquid drawol' valve 40.

To obtain the desired temperature at the top of the rerun tower, controlled portions of the liquid distillate may be withdrawn from the receiving tank 22 and recycled by means ofthe pump 41 and return line 42 regulated by a valve 42 to supply the liquid distillate into the top of the rerun tower, thereby returning suflicient amounts of the liquid distillate to maintain the desired temperature at the top of the tower and further supply a li uid medium to the towerwhich has the e ect of retarding the passage of certain heavy objectionable fractions which would otherwise pass over to the receiver and form an objectionable constituent in the final distillate.

It is to be noted that the feed to the tower is introduced at a point intermediate between the top and bottom. The vapor from the dephlegmator is led through a cooler the top of the rerun tower as refluxing medium. In order to strip the pressure distillate bottoms of gasoline it will probably be necessary to provide heat at the bottom of the tower and for this purpose saturated or 'superheated steam may be injected into the lower section of the tower as shown in the sketch. It is also possible to supply this heat by means of a re heated still which may take the form of a pipe or tube `rstill separately fired or located in the flues of the cracking unit where waste heat will be recovered.

Since by use of this scheme there will be no pressure distillate condensate to recirculate to the top of the dephlegmator, it is necessary to provide some other means of refluxing and it is proposed to incorporate a partial condenser in the top of the dephlegmator. This condenser will be in the form of atubular condenser, as shown in the sketch, or a coil condenser and may employ as a cooling medium either water or raw oil entering the system.

As an illustrative run, a Mid-Continent gas oil having a BaumeJ gravity of 31 was introduced and heated to a temperature of from 700 to 900 F., in the heating coil, thence passed to the expansion chamber, and the vapors dephlegmated in the column 8 as explained. The temperature of the vapors leaving the top of the dephlegmator was substantially 550 F. The temperature of the vapors leaving the cooler between the dephlegmator and rerun tower ranged from 400 to 500 F., while the temperature at the top of the rerun tower was substantially 350 F. The temperature at the bottom of the rerun tower using superheated steam was substantially 450 F., while if extraneously heated a temperature of 550 is advisable. The pressure during operation upon the cracking portion of the still was substantially 125 pounds per square inch. Under these conditions a high quality of Navy specification distillate was produced in the receiving tank 22.

I claim as my invention:

1. An oil conversion process, consisting in subjecting the oil to cracking conditions of temperature and pressure, in subjecting the evolved vapors to reliux condensation in a reflux condenser, in re-cracking the reiux condensate, in passing the vapors from the reflux condenser to a partial condenser, in fractionating the vapors and liquid passing from the partial condenser, in introducing steam to the vapors and liquid undergoing fractionation, and in condensing and collecting the uncondensed vapors after fractionation as gasoline-like products.

2. A continuous oil conversion process, consisting in subjecting the oil to cracking conditions of temperature and pressure in a cracking zone, in continuously passing the generated vapors from said cracking zone to a dephlegmator, in returning reflux condensate from said dephlegmator to the cracking zone, in passing the dephlegmated vapors from. said dephlegmator-to a primary condenser wherein only a portion of the vapors are condensed, in passing the uncondensed,

vapors and distillate to a zone of fractionatlon malntamed under a reducedpressure, and 1n introducing lnto sald zone of fractionation steam to commingle, with the vapors and distillate therein, in condensing the fractionated vapors, and in collecting the resulting gasoline-like product.

3. A continuous oil conversion process, consisting in subjecting the oil to cracking conditions of temperature and pressure in a cracking zone, in continuously passing the generated vapors from said cracking zone to a dephlegmator, in returning reflux condensate from said dephlegmator to the cracking zone, in passing4 the dephlegmated vapors from said dephlegmator to a partial condenser from which the vaporous and liquid constituents are passed to a zone of fractionation maintained under a reduced pressure, in introducing into said zone of fractionation steam to. commingle with the vaporous and liquid constituents therein, in condensing the fractionated vapors, in collecting the resulting gasoline-like product, and in-returning portions of said product to said fractionating zone to be re-vaporized therein. i

4. A hydrocarbon oil cracking process which comprises subjecting the oil to cracking conditions of temperature and pressure and separating evolved vapors from unvaporized oil, dephlegmating said vapors to condense fractions thereof substantially heavier than gasoline while retaining the gasoline-like pressure distillate in vaporous form, subsequently cooling the uncondensed vapors to a temperature between 400 F. and 500 F. and reducing the pressure thereon to slightly above atmospheric, introducing the lower resulting liquid and vaporous hydrocarbons into a 'fractionating zone for fractionation therein, applying a distillation heat to the ortion of said fractionating zone, maintalning in the upper portion of said zone a. temperature sufcient to permit gasolinelike hydrocarbons to. pass therefrom in vaporous form, removing gasoline-like vapors from the upper portion of said zone and subjecting the same to condensation.

5. A hydrocarbon oil cracking process which comprises subjecting the oil to cracking conditions of temperature and pressure and separating evolved vapors from unvaporized oil, dephlegmating said vapors to condense fractions thereof substantially heavier than gasoline while retaining the gasoline-like pressure distillate in vaporous form, subsequently cooling the uncondensed vapors to a temperature between 400 F. and

500 F. and reducing the pressure thereon to slightly above atmospheric, introducing the resulting liquid and vaporous hydrocarbons into a fractionating zone for fractionation therein, applying a distillation heat to the lower portion. of said fractionating zone, maintaining in the upper portion of said zone a temperature sufiicient to permit gasolinelike hydrocarbons to pass therefrom in vaporous form, removing gasoline-like vapors from the upper portion of said zone and subjecting the same to condensation thereby forming condensate, and returning a portion of said condensate to said fractionating zone.

6. A hydrocarbon oil cracking process which comprises subjecting the oil to cracking conditions of temperature and pressure and separating evblved vapors from unvaporized oil, dephlegmating said vapors to condense fractions thereof substantially heavier than gasoline while retaining the gasoline-likepressure distillate in vaporous form, subsequently partially condensing the uncondensed vapors, whereby only a portion of the gasoline-like vapors are condensed, introducing the resulting liquid and vaporous hydrocarbons into a fractionating zone for fractionation therein, applying a distillation heat to the lower portion of said fractionating zone, maintaining in the upper portlon of said zone a temperature suiiicient to perniit gasoline-like hydrocarbons to pass therefrom in vaporous form, removing gasoline-like va-v pors from the upper portion of said zone and subjecting the same to condensation.

7. A hydrocarbon oil cracking process which comprises subjecting the oil to cracking conditions of temperature and pressure and separating evolved vapors from unvaporized oil, dephlegmating said vapors to condense y,fractions thereof substantially heavier,than gasoline while retaining the lgasoline-like pressure distillate in vaporous which comprises subjecting the oil to cracking conditions of temperature and pressure thereby forming a vaporous hydrocarbon mixture, dephlegmating said vaporous mixture to condense fractions thereof substantially heavier than gasoline while retaining the gasoline-like pressure distillate in vaporous form, passing the vaporous pressure distillate to a cooling zone and lowering the temperature thereof at least 100 F. in said zone, thereby condensing a portion of said distillate, removing the pressure distillate from said zone and introducing the same to a fractionating zone for fractionation therein, applying a distillation heat to the lower portion of said fractionating zone, maintaining in the upper portion of said zone a tempera` ture suicient to permit gasoline-like hydrocarbons to pass therefrom in vaporous form,

removing gasoline-like vapors from the upper portion of said zone and subjecting the same to condensation.

CLAUDE IF. TEARS. 

